Learning to ride 2-wheel vehicles, specifically bicycles and mini-motorcycles, represents a very important step in a child's life. Although riding such vehicles is per se relatively easy, the child has, when he/she begins to learn, neither the necessary sense of balance, nor an even intuitive knowledge of which variables he/she must adjust to be able to maintain the desired riding conditions. As a proof thereof, being able to ride a bicycle is in common use the paradigm of what one learns with effort and which, however, is not forgotten once acquired.
In order to initiate the child to riding a bicycle, the most widespread method is to get him/her to ride a bicycle, for the first few years having two trainer wheels, usually applied to the sides of the rear drive wheel of the bicycle and parallel to said wheel, which allow a stable support of the bicycle on four wheels, i.e. the two large wheels and the two wheels which make up the stabilizers. The child thus learns to cycle, to brake and to swerve, with risks of falls being virtually negligible. Once the child is familiar with the simpler operations, the wheels are removed and the child is encouraged to ride without the trainer wheels, holding his/her bicycle upright upon start and then letting it go. This operation is more complex, it often implies falls of the child and it is not equally intuitive for every child; as a matter of fact, there are children who, upon being allowed to ride independently, do not understand that they must continue and tend to stop cycling, so that the fall is virtually guaranteed.
GB 265 490 relates to a safety device for motorcycles which provides a support wheel on a fork-shaped oscillating arm on both sides of the rear wheel. The two downward-curved arms are apt to oscillate vertically upwards and are retained downwards by spiral wings, thus helping to maintain ground contact of the rear wheel of the motorcycle. An arrangement of this type has no didactic usefulness.
FR 922 237 discloses a system of stabilizer wheels which can be attached and removed at will, with springs to maintain the wheels in the desired position (with or without stabilizer wheels) during the ride. The system allows to choose the desired degree of stability, but allows no adjustment of the wheel support: as a matter of fact, it limits itself to identify an operation position of the stabilizers and a home position for the stabilizers.
U.S. Pat. No. 2,793,877 discloses a system which provides a pair of wheels carried by respective flat springs, integral with two rigid shelves fastened to the bicycle frame, so that the wheel inclination may be adjusted during the ride, depending on the attitude and on the ground conditions.
U.S. Pat. No. 3,877,727 discloses a system comprising a pair of stabilizer wheels carried by supports on each side of the bicycle. The supports comprise a first shelf fastened to the frame, a second shelf which comes down from said first shelf, a third shelf which carries a circular terminal plate and which supports the wheel, the relative rotation between the second and the third shelf bringing the wheel between engagement position with the ground and a retracted, raised position.
U.S. Pat. No. 5,100,163 and U.S. Pat. No. 5,064,213 disclose a pair of stabilizer wheels carried by a square-shaped support, with a third elastic arm, which compensates the stresses in a diagonal direction.
A similar system is disclosed in U.S. Pat. No. 5,352,403, which relates to a system of stabilizer wheels, carried by a shelf consisting of three arms arranged trapetium-like, the last side of the trapetium being a spring element which, at one end, terminates on the arm carrying the trainer wheel. Thereby, the trainer wheel compensates riding irregularities.
WO95/09 759 discloses a dampener for articulated elements, having a first element articulated to a second element. The dampener has an elastic element, shaped so as to stay between the first and the second element, near the articulation region thereof and capable of engaging in an opposite manner with the first and the second element, so as to give a thrust to withstand the hinging of the first element towards the second element to dampen the movement of the first element towards the second element.
WO98/04 452 relates to an attachment for trainer wheels which may be removably fastened to the sides of the bicycle. The wheel support is bent, so as to thereby obtain the desired shape and size, such as, for example, a helical spring, so as to always maintain contact with the ground.
U.S. Pat. No. 6,331,012 discloses a pair of stabilizer wheels which has means for the height adjustment of the shelf which carries the wheel, which is introduced in the vertical portion of the support.
Finally, WO2005/061 317 discloses a system with two stabilizer wheels, carried by two square shelves, the two arms of which are articulated in a yielding, C-shaped structure which moves elastically, as a reaction to the stresses of the ride.
All the documents set forth above solve very well the problem of a stable ride, but are not particularly useful to learn to ride bicycles and motorcycles.